The present invention concerns seating units having a reclineable back, and more particularly concerns seating units having a reclineable back and a forwardly movable/tillable seat that moves with a synchronous movement as the back is reclined.
A synchrotilt chair is described in U.S. Pat. Nos. 5,050,931, 5,567,012; 4,744,603; and 4,776,633 (to Knoblock et al.) having a base assembly with a control, a reclineable back pivoted to the control, and a seat operably mounted to the back and control for synchronous motion as the back is reclined. This prior art chair incorporates a semi-rigid flexible shell that, in combination with the chair support structure, provides a highly-controlled postural support during the body movements associated with tasks/work (e.g., when the back is in an upright position) and during the body movements associated with recline/relaxation (e.g., when the chair is in a reclined position). This prior art chair moves a seated user""s upper body away from the user""s work surface as the user reclines, thus providing the user with more area to stretch. However, we have discovered that often users want to remain close to their work surface and want to continue to work at the work surface, even while reclining and relaxing their body and while having continued postural support. In order to do this in the synchrotilt chair of U.S. Pat. No. 5,050,931, users must scoot their chair forwardly after they recline so that they can still easily reach their work surface. They must also push away when they move back to an upright position to avoid being pushed against their work surface. xe2x80x9cScootingxe2x80x9d back and forth once or twice is perhaps not a serious problem, but often users, such as office workers using computers, are constantly moving between upright and reclined positions, such that the process of repeatedly scooting back and forth becomes annoying and disconcerting. In fact, moving around and not staying in a single static position is important to good back health in workers whose jobs require a lot of sitting.
Another disadvantage of moving a seated user""s upper body significantly rearwardly upon recline is that the user""s overall center of gravity moves rearward. By providing a more constant center of gravity, it is possible to design a reclineable chair having greater recline or height adjustment without sacrificing the overall stability of the chair. Also, reclineable chairs that move a seated user""s upper body significantly rearwardly have a relatively large footprint, such that these chairs may bump into furniture or a wall when used in small offices or in a compact work area. Still another disadvantage is that large springs are required in these existing reclineable chairs for back support, which springs are difficult to adjust due to the forces generated by the springs. However, the tension of these springs preferably should be adjustable so that heavier and lighter weight users can adjust the chair to provide a proper amount of support.
Concurrently, seated users want to be able to easily adjust the spring tension for providing support to the back during recline. Not only do heavier/larger people need greater/firmer back support than lighter/smaller people, but the amount of support required changes at a greater rate during recline. Specifically, lighter/smaller people need a lesser initial level of support as they begin to recline and need a moderately increased level of support as they continue to recline; while heavier/larger people need a significantly higher minimum initial level of support as they begin to recline and need a significantly increased level of support as they continue to recline. Restated, it is desirable to provide a chair that is easily adjustable in its initial level of support to the back during initial recline and that automatically also adjusts the rate of increase in support during recline. Further, it is desirable to provide a mechanism to allow such an easy adjustment (1) while seated; (2) by a relatively weaker person; (3) using easily manipulatable adjustment controls; and (4) while doing so with a control that is not easily damaged by a relatively strong person who may xe2x80x9covertorquexe2x80x9d the control. Further, a compact spring arrangement is desired to provide optimal appearance and to minimize material cost and part size.
Manufacturers are becoming increasingly aware that adequate lumbar support is very important to prevent lower back discomfort and distress in workers who are seated for long periods. A problem is that the spinal shape and body shape of workers vary tremendously, such that it is not possible to satisfy all workers with the same shape. Further, the desired level of firmness or force of support in the lumbar area is different for each person and may vary as a seated user performs different tasks and/or reclines in the chair and/or becomes fatigued. In fact, a static lumbar support is undesirable. Instead, it is desirable to provide different lumbar shapes and levels of support over a workday. Accordingly, an adjustable lumbar system is desired that is constructed to vary the shape and force of lumbar support. At the same time, the adjustable lumbar system must be simple and easy to operate, easily reached while seated, mechanically non-complex and low cost, and aesthetically/visually pleasing. Preferably, adjustment of the shape and/or force in the lumbar area should not result in wrinkles in the fabric of the chair, nor unacceptable loose/saggy patches in the fabric.
Modern customers and chair purchasers demand a wide variety of chair options and features, and a number of options and features are often designed into chair seats. However, improvement in seats is desired so that a seated user""s weight is adequately supported on the chair seat, but simultaneously so that the thigh area of a seated user is comfortably, adjustably supported in a manner that adequately allows for major differences in the shape and size of a seated user""s buttocks and thighs. Additionally, it is important that such options and features be incorporated into the chair construction in a way that minimizes the number of parts and maximizes the use of common parts among different options, maximizes efficiencies of manufacturing and assembling, maximizes ease of adjustment and the logicalness of adjustment control positioning, and yet that results in a visually pleasing design.
Accordingly, a chair construction solving the aforementioned problems is desired.
In one aspect, a seating unit includes a base assembly, a back frame pivoted to the base assembly at a back pivot for movement between plurality of positions including upright and reclined positions, and a seat pivoted to the back frame at a seat pivot spaced rearwardly and below the back pivot. The seat is slidably supported at a front portion of the base assembly for horizontal movement. The back pivot and the seat pivot are interconnected and arranged to move the seat generally forwardly and also to move a rear portion of the seat downwardly with a synchronous pivoting motion as the back frame is reclined, whereby a seated user is comfortably supported in the upright and reclined positions. The base assembly includes a control housing with an energy mechanism positioned therein that operably engages one of the back frame and the seat for biasing the back frame to the upright position. The seat includes a seat slide member that slidably engages the control housing, and further includes a seat support carrier pivotally engaging the seat slide at first pivots and pivotally engaging the back frame at second pivots.
In another aspect, a seating unit includes a base assembly, a back frame pivoted to the base assembly at a back pivot for movement between a plurality of positions including upright and reclined positions, and a seat pivoted to the back frame at a seat pivot spaced rearwardly and below the back pivot. The seat is slidably supported at a front portion of the base assembly for horizontal movement. The back pivot and the seat pivot are interconnected and arranged to move the seat generally forwardly and also to move a rear portion of the seat downwardly with a synchronous pivoting motion as the back frame is reclined, whereby a seated user is comfortably supported in the upright and reclined positions. The base assembly includes a control housing with an energy mechanism positioned therein that operably engages one of the back frame and the seat for biasing the back frame to the upright position. A back-stop mechanism is attached to the control housing and configured to selectively engage the seat to limit forward movement of the seat and accordingly selectively limit recline of the back frame.
In yet another aspect, a seating unit includes a base assembly, a back frame pivoted to the base assembly at a back pivot for movement between a plurality of positions including upright and reclined positions, and a seat pivoted to the back frame at a seat pivot spaced rearwardly and below the back pivot. The seat is slidably supported at a front portion of the base assembly for horizontal movement. The back pivot and the seat pivot are interconnected and arranged to move the seat generally forwardly and also to move a rear portion of the seat downwardly with a synchronous pivoting motion as the back frame is reclined, whereby a seated user is comfortably supported in the upright and reclined positions. The base assembly includes a control housing with an energy mechanism positioned therein that operably engages one of the back frame and the seat for biasing the back frame to the upright position. The base assembly includes side arms that extend upwardly generally adjacent the seat for supporting the back frame and a portion of the seat. The back frame is pivoted to the side arms. The seat is pivoted to the back frame in a location generally proximate the side arms. The energy mechanism includes a spring positioned transversely in the control housing, and includes a lever operably connecting the spring to the one of the seat and the back frame.
In yet another aspect, a seating unit includes a base assembly, a back frame pivoted to the base assembly at a back pivot for movement between a plurality of positions including upright and reclined positions, and a seat pivoted to the back frame at a seat pivot spaced rearwardly and below the back pivot. The seat is slidably supported at a front portion of the base assembly for horizontal movement, with the back pivot and the seat pivot being interconnected and arranged to move the seat generally forwardly and also to move a rear portion of the seat downwardly with a synchronous pivoting motion as the back frame is reclined. By this arrangement, a seated user is comfortably supported in the upright and reclined positions. The base assembly includes a control housing with an energy mechanism positioned therein that operably engages one of the back frame and the seat for biasing the back frame to the upright position. The energy mechanism includes a spring positioned transversely within the control housing, and a lever operably connects the spring to one of the seat and the back frame. The lever is pivotable about a vertical axis with a first end engaging the spring and a second end operably connected to the seat for biasing the seat rearwardly and in turn for biasing the back frame to the upright position.
In yet another aspect, a seating unit includes a base assembly having a control housing, a back pivoted to the base assembly for movement between upright and reclined positions, and a seat operably supported on the base assembly and connected to the back for movement between a substantially rearward position and a forward position. The seat includes a front portion that is slidably connected to the base assembly to move horizontally forwardly upon recline of the back so that a seated user""s legs are not undesirably lifted from a floor surface during recline. The seat further includes a rear portion flexibly connected to the front portion and that is operably connected to the back to move downwardly and forwardly upon recline so that the seated user is comfortably and posturally supported during recline with an angular synchronous movement of the seat and the back, and so that a maximum forward movement of the seat and maximum angular movement of the back are limited to strokes that keep the hands of a seated user relatively constant during recline. A spring mechanism is positioned transversely in the control housing, and further includes a lever pivotally engaging the spring mechanism and operably connected to the seat for biasing the seat toward the rearward position and simultaneously biasing the back toward the upright position. The control housing includes side arms, and the seat includes bearings that slidably engage the side arms.
In yet another aspect, a seating unit includes a base assembly, a unitary back frame pivoted to the base assembly at a back pivot for movement as a unit between a plurality of positions including upright and reclined positions, and a seat pivoted to the back frame at a seat pivot spaced rearwardly and below the back pivot. The seat is slidably supported at a front portion of the base assembly for horizontal movement, the back pivot and the seat pivot being interconnected and arranged to move the seat generally forwardly and also move a rear portion of the seat downwardly with a synchronous pivoting motion as the back frame is reclined. By this arrangement, a seated user is comfortably supported in the upright and reclined positions.
In yet another aspect, a seating unit includes a base assembly, a back including a unitary back frame pivoted to the base assembly for movement as a unit between upright and reclined positions, and a seat operably supported on the base assembly and connected to the back frame for movement between a substantially rearward position and a forward position. The seat includes a front portion that is slidably connected to the base assembly to move horizontally forwardly upon recline of the back so that a seated user""s legs are not undesirably lifted from a floor surface during recline. The seat further includes a rear portion flexibly connected to the front portion and that is operably connected to the back to move downwardly and forwardly upon recline so that the seated user is comfortably and posturally supported during recline with an angular synchronous movement of the seat and the back, and so that a maximum forward movement of the seat and maximum angular movement of the back are limited to strokes that keep the hands of a seated user relatively constant during recline.
In yet another aspect, a seating unit includes a base assembly having a control housing, an energy source located within the control housing, and a seat operably supported on the base assembly for generally horizontal movement between forward and rearward positions, with the seat operably interconnected to said energy source. A back support includes a back shell and a unitary back frame supporting the back shell. The back frame includes a first pivot where the back frame is pivotally coupled to the base assembly for movement as a unit between upright and reclined positions, and a second pivot where the back frame is pivotally coupled to the seat. The energy source biases the back support into an upright position by urging the seat rearward, said rearward movement of the seat inducing the back support to rotate to a generally upright position at the first pivot.
In still another aspect, a seating unit includes a base assembly having side arms, a unitary back frame pivoted to the base assembly at back pivots for movement as a unit between a plurality of positions including upright and reclined positions, and a seat pivoted to the back frame at seat pivots and slidably supported at a front portion of the seat assembly. The back frame includes right and left configured end sections positioned on opposite sides of the seat and between the sides of the seat and associated ones of the side arms, the configured end sections supporting first pivot bearings at the seat pivots and second pivot bearings at the back pivots.
In one aspect, a seating unit includes a base assembly having a control housing and upwardly-extending side arms, an inverted U-shaped back frame having configured end sections positioned adjacent associated ones of the side arms and pivoted thereto at back pivots, the back pivots each comprising a first stud and a rotatable first bearing engaging the first stud, and a seat slidably supported on the control housing. The seat includes a seat carrier pivoted to the configured end sections at seat pivots. The seat pivots each include a second stud and a rotatable second bearing engaging the second stud. The seat pivots and back pivots are spaced apart. An adjustable energy mechanism includes a transverse spring, a lever operably engaging the spring and the seat for biasing the seat toward a rearward position and in turn biasing the back frame toward an upright position, and an adjustment pivot member adjustably engaging the lever to define a fulcrum that moves during recline and that is manually adjustably changeable to relocate the fulcrum for adjustably controlling a force of the spring on the seat.
In one aspect, a seating unit includes a base assembly having a control housing, an energy source located within the control housing, and a seat operably supported on the base assembly for generally horizontal movement between forward and rearward positions, with the seat operably interconnected to said energy source. A back support includes a back shell and a back frame supporting the back shell. The back frame includes a first pivot where the back frame is pivotally coupled to the base assembly for movement of the back support between upright and reclined positions, and a second pivot where the back frame is pivotally coupled to the seat. The energy source biases the back support into an upright position by urging the seat rearward, said rearward movement of the seat inducing the back support to rotate to a generally upright position at the first pivot. A variable back-stop mechanism is supported on the base assembly and operably engages the seat, the variable backstop mechanism being configured to concurrently stop the seat and stop recline of the back support at a plurality of selectable positions between the upright and reclined position.
In one aspect, a seating unit includes a base assembly having a control housing, an energy source located within the control housing, and a seat operably supported on the base assembly for generally horizontal movement between forward and rearward positions, with the seat being operably interconnected to said energy source. The seat includes a seat shell having a rear section adapted to support buttocks of a seated adult user and a front section adapted to support thighs of the seated adult user. A back support includes a back shell and a unitary back frame supporting the back shell. The back frame includes a first pivot where the back frame is pivotally coupled to the base assembly for movement as a unit, and a second pivot point where the back frame is pivotally coupled to the seat.
These and other features and advantages of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.